Isolation and Characterization of Acetoacetic Bacteria from Decomposed Fruits

Abstract

INTRODUCTION: Acetic Acid Bacteria (AAB) are rod shaped, aerobic and gram-negative bacteria. They have ability to oxidize ethanol to acetic acid. They are widely distributed in natural habitats and classified into the family acetobacteraceae. Members of this family are useful in Industrial production of vinegar. 1,2&3 In past there were two main genera-Acetobacter and Glucanobacter but at present there are twelve genera which are in the family acetobacteraceae i.e. Acetobacter, Glucanobacter, Acidomonas, Gluconaerobacter, Asaia, Kozakia, Swaminathania, Saccharibacter, Neoasaia, Granulibacter, Tanticharoenia and Ameyamaea. 4 The genus acetobacter that is primarily used in vinegar manufacturing. The main difference between Acetobacterand Gluconobacteris that Acetobactercan oxidizes acetate to CO 2 and H 2 O, while Gluconobacter cannot oxidize it. Vinegar is defined as a 4%acetic acid solution produced by the alcoholic fermentation process using sugary substances by acetic acid producing bacteria. These are very important in industrial production of vinegar. These bacteria are generally found in nature associated with some fruits such as grapes and are normally present in decomposed fruits. There are several factors that affect the growth and survival of AAB. These include ethanol concentration, acetic acid concentration, oxygen, temperature and nutrient availability are the most important factors that can affect the survival of AAB. The thermo tolerant strains were able to oxidize ethanol concentration without any appreciable lag time; they worked very rapidly with a higher fermentation rate. Acetobacteraceti has not yet been reported as a pathogenic microbe to humans or animals. It does not produce any toxins, enzymes, or any viruses that harm any human or animal. It is ubiquitous in nature and there is contact of this bacterium on all animals on a frequent basis. Acetobacteraceti is known to cause rotting and browning discoloration in fruits such as apples, pears and citrus products. These bacteria can be isolated from vinegar alcoholic beverages, decomposed fruits, flowers, honey, sugarcane, fruit juice, soil and water etc. 3 & 5 There are various factors that affect the growth and survival of acetic acid bacteria like ethanol concentration, pH, oxygen, temperature and availability of nutrients, carbon source etc. De